Prof. Dr. Mark Maraun
Population dynamics and the trophic plasticity of oribatid mites along forest land use gradients remain elusive. This project comprises three working packages.
1. Temporal dynamics of soil living oribatid mites in different forest ecosystems along a land use gradient.
2. The role of land use on the trophic ecology of oribatid mites using neutral lipid fatty acid analysis (NLFAs). The study will contribute to the understanding of the niche width and the trophic plasticity of oribatid mites.
3. The influence of nutrient addition on oribatid mite communities of dead wood along a land use gradient (BeLongDead subproject). We closely cooperate with the project of Stefan Scheu (LitterLinks), and with the BeLongDead consortium (coordinated by Wolfgang Weisser).
Understanding the structure and functioning of soil animal communities is of prime importance for understanding the functioning of soil systems in general. In the last years oribatid mites became one of the model organisms for understanding the ecology of this very diverse (> 10,000 species) and abundant (20,000 - 400,000 ind./m²) soil living animal taxon. However, despite considerable progress in understanding the trophic ecology (Maraun et al. 2011), the reproductive biology (Maraun et al. 2012), factors that affect their community assembly (Caruso et al. 2012) and their dispersal abilities (Lehmitz et al. 2011, 2012), many factors affecting oribatid mite communities remain little studied. The least understood aspects of oribatid mite ecology include (a) temporal population dynamics, (b) trophic niches, and (c) reproductive mode, i.e. the exceptionally high number of parthenogenetic species and individuals in soil. This study aims at further closing our gap of knowledge with regard to the ecology of this important soil animal taxon.
The following main hypotheses will be investigated:
1. Densities of parthenogenetic oribatid mites fluctuate more than those of sexual oribatid mites since the density of parthenogenetic ‘species’ is mainly driven by density-independent factors (since they do not experience resource limitations; cf. Scheu and Drossel 2007)
2. Parthenogenetic oribatid mites generally occupy lower positions in food webs, i.e. tend to be detritivores (i.e., primary decomposers feeding on plant litter) and not fungal feeders or predators; in contrast to the latter, detritivores are assumed to be structured predominantly by density independent factors.
3. Increased availability of nutrients will shift the community structure of bark-living oribatid mites from sexual species (regulated by density dependant factors) towards more parthenogenetic species (less affected by density dependent factors). The latter experiment is carried out on the bark of trees since oribatid mites in this habitat are dominated by sexual individuals (90-95 %; Erdmann et al. 2006; Fischer et al. 2010b), and changes towards more parthenogenetic species is easier to study than in soil where most individuals reproduce via parthenogenesis (80–95 %; Maraun et al. 2003; Cianciolo and Norton 2006).
Project related publications
Ehnes RB, Pollierer MM, Erdmann G, Klarner B, Eitzinger B, Digel C, Ott D, Maraun M, Scheu S, Brose U (2014) Lack of energetic equivalence in forest soil invertebrates. Ecology 95, 527-537
Maraun M, Augustin D, Müller J, Bässler C, Scheu S (2014) Changes in the community composition and trophic structure of microarthropods in sporocarps of the wood decaying fungus Fomitopsis pinicola along an altitudinal gradient. Applied Soil Ecology 84, 16-23
Wehner K, Scheu S, Maraun M (2014) Resource availability as driving factor of the reproductive mode in soil microarthropods (Acari, Oribatida). PLoS ONE 9: e104243
Heidemann K, Ruess L, Scheu S, Maraun M (2014) Nematode consumption by mite communities varies in different forest microhabitats as indicated by molecular gut content analysis. Experimental and Applied Acarology 64, 49-60
Klarner B, Maraun M, Scheu S (2013) Trophic diversity and niche partitioning in a species rich predator guild - natural variations in stable isotope ratios (13C/12C, 15N/14N) of mesostigmatid mites (Acari, Mesostigmata) from Central European beech forests. Soil Biology and Biochemistry 57, 323-333
Birkhofer K, Schöning I, Alt F, Herold N, Klarner B, Maraun M, Marhan S, Oelmann Y, Wubet T, Yurkov A, Begerow D, Berner D, Buscot F, Daniel R, Diekötter T, Ehner RB, Erdmann G, Fischer C, Foesel B, Groh J, Gutknecht J, Kandeler E, Lang C, Lohaus G, Meyer A, Nacke H, Näther A, Overmann J, Polle A, Pollierer MM, Scheu S, Schloter M, Schulze ED, Schulze W, Weinert J, Weisser WW, Wolters V, Schrumpf M (2012) General relationships between abiotic soil properties and soil biota across spatial scales and different land-use types. PLoS ONE 7(8), e43292
Maraun M, Norton RA, Ehnes R, Scheu S, Erdmann G (2012) Positive correlation of density and parthenogenetic reproduction in oribatid mites supports the “Structured Resource Theory of Sexual Reproduction”. Evolutionary Ecology Research 14, 311-323
Erdmann G, Scheu S, Maraun M (2012) Regional factors rather than forest type drive the community structure of soil living oribatid mites (Acari, Oribatida). Experimental and Applied Acarology 57, 157–169
Maraun M, Erdmann G, Fischer BM, Pollierer MM, Norton RA, Schneider K, Scheu S (2011) Stable isotopes revisited: their use and limits for oribatid mite trophic ecology. Soil Biology and Biochemistry 43, 877-882
Previous project contribution of PD Dr. Mark Maraun: Frass